Originally Posted by yonderboy

With special freewheel cranks. They have threads on them instead of a spider, but a couple brands have spiders you can put on in place of a freewheel. They're mostly for mod frames that have integrated bashguards.

http://www.echobike.com/team2004/team2004sideview.jpg , for them mounted. Other mod frames have deraileurs, or they run them on stock rides.

http://www.norco.com/05/2005bikes/bi...ges/evolve.jpg